Capacitance fuel guages

[geoffreylewis]

I have 3 Vision Microsystems capacitance probes fitted, the system was working correctly. I have wired them correctly, supplied 5V as per the previous kit, but when I add fuel to calibrate, there is no variation in the voltage, measured at the probe, has anyone had this problem before, it has been sugested that the probes/system requires a resistor between the earth and the white output wire, but of what size?
Help will be very much appreciated.

 

[mmarien]

When I calibrated my Princeton capacitive fuel probe Skyview complained that it didn't detect a change when I added ten litres. The difference was about 0.1 volts. I ignored the warning for every add and my fuel gauge works fine. I think I seen somewhere on this forum that the resolution Skyview can detect is 0.001 volts.

The calibration screen shows the voltage it detects. If you can see that it's different from the last add then just ignore the Skyview warning.

 

[Dynon]

I think - but am not certain - that those have a frequency output. If that's the case, they're not compatible with our products, unfortunately, which require DC voltage output from capacitance fuel level sensors.

 

[jakej]

I think - but am not certain - that those have a frequency output. If that's the case, they're not compatible with our products, unfortunately, which require DC voltage output from capacitance fuel level sensors.

DS - I believe they are the frequency type, he'll need a frequency to voltage converter

JakeJ

 

[geoffreylewis]

Thanks, I believe you are correct, and I need a frequency to voltage converter. Does anyone know where I might buy some or what the component parts are to have some made up.
Many thanks again

 

[jakej]

Thanks, I believe you are correct, and I need a frequency to voltage converter. Does anyone know where I might buy some or what the component parts are to have some made up.
Many thanks again

Just google "frequency to voltage converter" but don't forget you need it for a max output of 5 volts

JakeJ

 

[rick789pb]

I also have the Vision Microsystem fuel probes and I purchased (2) Princeton Capacitance Convertors and still cannot get the voltage values to change when I add fuel to either main or header tanks. I have had (2) experts do and reconfirm the wiring which they say is correct and still cannot calibrate. Any suggestions?

Rick789

 

[Dynon]

The vision microsystems probes output a frequency (pulses). Our products are not directly compatible with frequency-based outputs. Unfortunately, the capacitance converters you have are designed to convert capacitance signals to a voltage. They're also not compatible with frequency-based fuel level sensors like the vision ones (unless they have some capability that we're not aware of).

You'd need a frequency to voltage converter to get this working. We don't have an off-the-shelf product to point your to that we know to work without some electronics knowledge.

 

[skysailor]

The converters from Princeton need to be calibrated first. I will do that this week. Basically, the process is that you put the converter into calibration mode and set the "empty" point. You then completely fill the tank and set the "full" point on the converter. Now, empty the tank. Put the Dynon in calibrate mode. It will have you add fuel back in steps telling when you have completed each step. When you finish the Dynon calibration your fuel gauges will work.

 

[mmarien]

You can get the Princeton fuel probes that don't need calibration prior to calibrating with Dynon. Order it with just one set point. Reset it with an empty tank and it's ready for the Dynon calibration.

 

[rick789pb]

I have two Princeton Fuel Capacitors one for the header tank and one for the main tank. Both are single set point and I still cannot get a voltage value change when I add fuel per instructions. Can anyone help?

 

[mmarien]

Have you done the single point calibration with an empty tank?

 

[skysailor]

Make sure the Dynon thinks the probe is a capacitive probe even though you have the voltage/frequency converter. The single set point mode of the CP10A converter (only empty) works fine. I just did my Glasair this weekend with the same Vision Microsystems capacitive probe and CP10A converter. It works great. Shoot me a note if I can help.

 

[PlaneDan]

:'( I was doing the set up for Fuel and found that there is only a choice of "Resistive"  I have Princeton Probes.  I had these when I installed my D10 and had no problems with the configuration.  How do I tell the SV that I have Capacitance probes ( senders )?  I just installed the new sensor definitions today.

 

[PlaneDan]

So, you calibrated your fuel with capacitance probes. How did you tell the SV that you were using capacitance? The only choice I have on mine is Resistive???? :-/

 

[Dynon]

So you need to first make sure you've chosen a type C input, (any of pins 8,22,23,31) on the EMS D37. Then, when you do your pin mapping in the EMS setup, you have to make sure that those pins are set to the FUEL LEVEL (CAPACITIVE) type.

 

[PlaneDan]

Thanks, I guess I just thought that the sensors were on the pins that I put them on. I deleted those and added them to pins 22 and 23. You can see in the attachments that they are now recognized. However, now I am having real problems getting them calibrated. I did exactly the same thing with my D10 and had ZERO problems, but this time it is not going so well.

In the 756.bmp, you can see 4.95 Voltage, don't know what that means. You can also see .04 volts for each point, don't know what that means. But you can see an additional gallon for each point for a total for 10.6 gallons.

Then look at 008.bmp and you can see 0.0 gallons added. After adding the last .6 gallon, it complained that I had not added a full gallon and did I want to take it anyway. I said yes, and then pushed FULL. It then complained that the calibration was not successful. The same thing happened with the right tank.

078.bmp shows the results. Even though the left tank is showing full, it shows that it is not CAL. The right tank does not show full, does not show CAL, and keeps fluctuating. Notice that it also shows 4.8 gallons remaining even though it knows that I just added 21.3 gallons.

I know I must have done something wrong, but have no clue what it was. It is no picnic draining tanks and getting the fuel truck to come over and add it back 1 gallon at a time, so the next time I have to get it right.

I will appreciate any assistance you can give me in this task, so I can get it right next time. Thank you.

 

[Dynon]

Fundamentally, that means that SkyView is not seeing any change in voltage from the sensors as fuel is being added (down to 1/100th of a volt). Assuming you used these same sensors with your EMS-D1-, did you happen to write down the calibration numbers from that succesful calibration when you did it back when?

 

[PlaneDan]

No, it just worked. I was concerned about how it knew how much fuel I had added at each point. On the last pour, where I added only .6 gallon, it knew that I had not added a full gallon. Yes, these are the same fuel tanks and sensors that I had working on my D10 and they were working when I took the D10 out to install the SkyView.

 

[PlaneDan]

So, what do I do now? What test can I perform? No sense in doing the same thing over again. I have several friends who use resistance and have had no problems. Is this a common problem? I believe that I am almost finished with this major conversion to the SV, but this is really holding me up. I have a KR Gathering to fly this SV to on the 5th of October and everyone is anxious to see the SV in a KR. This may be the first and only, so far. Is it possible to make this work in another way than relying on the computer to figure it out? Sorry, I know I am grabbing at straws, but I really need a solution.